The present invention relates generally to seat restraint systems for vehicles and, more particularly, to a load limiting seat restraint retractor for a seat restraint system in a vehicle.
It is known to provide a seat restraint system such as a seat belt in a vehicle to restrain an occupant in a seat of the vehicle. In some vehicles, the seat restraint system may be a lap belt, a shoulder belt, or both. Typically, the lap belt and shoulder belt are connected together at one end. The seat restraint system includes a latch plate at the connected end. The seat restraint system also includes a buckle connected at one end by webbing or the like to vehicle structure. The buckle receives the latch plate to be buckled together. When the buckle and latch plate are buckled together, the seat restraint system restrains movement of the occupant to help protect the occupant during a collision.
It is also known to provide a load limiting retractor for the seat restraint system. During a front impact, the load limiting retractor locks and rapid deceleration causes forward movement of the occupant and the occupant to load the seat restraint webbing. These load limiting retractors are used to payout or unspool seat restraint webbing under a constant load and allow the occupant to decelerate with the vehicle, thus limiting high seat restraint loads, thereby improving occupant performance. However, these load limiting retractors typically offer one level of load limiting.
It is desirable to limit the amount of restraint load on an occupant during an impact for a seat restraint system in a vehicle. It is also desirable to provide a load limiting mechanism for a seat restraint retractor of a seat restraint system in a vehicle. It is further desirable to provide multiple levels of load limiting for various size occupants during an impact in a seat restraint system of a vehicle that uses a minimal number of parts for a mechanical device.
It is, therefore, one object of the present invention to provide a new load limiting seat restraint retractor for a seat restraint system in a vehicle.
It is another object of the present invention to provide a load limiting seat restraint retractor for a seat restraint system in a vehicle that achieves multi-level load limiting.
It is yet another object of the present invention to provide a load limiting seat restraint retractor for a seat restraint system in a vehicle that is mechanical and uses a minimal number of parts.
To achieve the foregoing objects, the present invention is a load limiting seat restraint retractor for a seat restraint system in a vehicle including a housing for operative connection to vehicle structure. The load limiting seat restraint retractor also includes a take-up spool operatively connected to the housing and connected to webbing of a seat restraint system for winding and unwinding the webbing. The load limiting seat restraint retractor further includes a torsion bar operatively connected to the housing to provide a constant load limiting on the webbing during an impact. The take-up spool is mounted on the torsion bar. The load limiting seat restraint retractor includes a locking mechanism operatively connected to the torsion bar and the housing. The load limiting seat restraint retractor includes a load limiting device disposed between the locking mechanism and the take-up spool to deform locally to provide digressive load limiting on the webbing during an impact.
One advantage of the present invention is that a load limiting seat restraint retractor is provided for a seat restraint system in a vehicle. Another advantage of the present invention is that the load limiting seat restraint retractor achieves multi-level load limiting and provides the desired effect of digressive load limiting. Yet another advantage of the present invention is that the load limiting seat restraint retractor offers a high peak load and digresses to a lower load level, thereby reducing the restraint load to a 5th percentile female. Still another advantage of the present invention is that the load limiting seat restraint retractor is a mechanical device for digressive load limiting using a minimal number of parts and cost.
Other objects, features, and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.